bug#13480: 24.3.50; `C-w' from Isearch should translate newlines to spaces

[Dani Moncayo <dmoncayo@gmail.com>]

>> So maybe a better default value for `search-upper-case'
>> would be `nil' instead of the current default `not-yanks'.
>
> I've just read the docstring of that variable, and I think its design
> is clearly misguided.  The text in the search string that came from a
> yank should not be treated differently from the rest.  I see no point
> in that approach.

Well, I see the point of making that distinction: If the user is
Isearching and _types_ an uppercase character, then it is quite
reasonable to assume that she wants the _current_ Isearch session to
be case-sensitive.  But that assumption is not reasonable when the
user takes text from somewhere (kill ring or buffer) and adds it to
the search string.

But downcasing the text in the second case is clearly a wrong
approach, because we are losing information that can be necessary
during the Isearch session for doing the right thing.

Instead, store the text in the search string as supplied, without
altering it in any way, and do the search based on it and the current
search "conditions", which can vary during the Isearch session.

-- 
Dani Moncayo